Magnetic ‘Braids’ May Cook the Sun’s Corona
Scientists have long puzzled over why the surface of the sun is cooler than its corona, the outer hazy atmosphere visible during a solar eclipse. Now thanks to a five-minute observation by a small, but very high-resolution ultraviolet telescope they have some answers.
Even before the July 2012 launch of the High-resolution Coronal Imager, nicknamed Hi-C, scientists suspected that magnetic fields on the sun were responsible for ramping up its energy, resulting in a flaring corona that can reach 7 million degrees Fahrenheit, compared to a visible solar surface temperature of about 10,000 degrees. Hi-C, which was launched aboard a suborbital rocket to study the sun without interference from Earth’s atmosphere, revealed interwoven magnetic fields braided like hair. When the braids relaxed, they released energy.